int swap_add(int *xp, int *yp) {
    int x = *xp;
    int y = *yp;

    *xp = y;
    *yp = x;

    return x + y;
}

int caller() {
    int arg1 = 123;
    int arg2 = 456;
    int sum = swap_add(&arg1, &arg2);
    int diff = arg1 - arg2;

    return sum * diff;
}

int main() {
    caller();
    return 0;
}